Cranks & Cranks Unless Gas Pedal Is Depressed.

I'm thinking my CPS is starting to fail as this happened about a year ago and I replaced the CPS with a jeep one, or I have a weak/dead battery.

I first noticed something was wrong (although I didn't realize it until later) when it was SLIGHTLY harder to start. You know that niche you get into when you know just how long to crank your xj for it to start? I'd do that and it'd either just BARELY catch and fire up or it would not start at all.

I drove a 400 mile trip over the weekend and played music out of the jeep for about 3 or so hours. Never put a battery charger on the battery. (Weak battery? Ill put it on a charger when I get home.)

This morning I noticed it wouldn't start unless I used the gas pedal to start it and physically idle it with my foot. Here's a video of it.

Posting from my phone now so when I get home I can begin troubleshooting it with the advice from .

http://youtu.be/Bsco4ukMoac

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

Disconnect the battery for ten minutes or so... it should be good to go.

Pretty common for a combination of sticky stuff inside the IAC and a weak electrical system (low battery) to cause the IAC to stick shut.

I periodically spray some penetrating oil (I use Henkel/Loc Tite five way spray) into the IAC opening with the motor running and repeat a few times as I work the throttle by hand a little. I even glued (a tiny drop of super glue) the red plastic tube extension onto the nozzle of the spray oil so there is title possibility of loosing it down the TB throat (I almost did that once ).

I've gotten so I spray some oil into the iAC opening a few times a years as a prophylactic measure and rarely have any issues.

Most times when my IAC started acting up it was shortly before the battery or the alternator failed. Seems the IAC needs all the voltage it can get, especially when it's sticky dirty, to function properly. The same with my Renix and HO, both seem to have this issue.

The issue usually stems from low voltage cranking that causes a memory malfunction in the ECU. Pretty common in Chryslers of all types.

8Mud said:

Pretty common for a combination of sticky stuff inside the IAC and a weak electrical system (low battery) to cause the IAC to stick shut.

I periodically spray some penetrating oil (I use Henkel/Loc Tite five way spray) into the IAC opening with the motor running and repeat a few times as I work the throttle by hand a little. I even glued (a tiny drop of super glue) the red plastic tube extension onto the nozzle of the spray oil so there is title possibility of loosing it down the TB throat (I almost did that once ).

I've gotten so I spray some oil into the iAC opening a few times a years as a prophylactic measure and rarely have any issues.

Most times when my IAC started acting up it was shortly before the battery or the alternator failed. Seems the IAC needs all the voltage it can get, especially when it's sticky dirty, to function properly. The same with my Renix and HO, both seem to have this issue.

Click to expand...

Alright that makes sense. So just spray the plunger with PB blaster a little bit and fully charge my battery?

Kingkong0192 said:

Alright that makes sense. So just spray the plunger with PB blaster a little bit and fully charge my battery?

Click to expand...

Works for me, at least in the short term. Though it often indicates some sort of deeper trouble in the charging system. May be just a low battery or may indicate a battery or alternator on the way out.

I've had the alternator fail twice and the battery once and all three times I had IAC issues before they completely took a dump.

I've also had the IAC get full (over the years) of sticky stuff and act up, especially in cold weather.

I am glad you all know what year jeep he has, but I don't.

IIRC there is a timer relay that resets the IAC when the engine is turned off on Renix, that causes the IAC to be set in the wrong location for restarts later. B+ relay?

Not sure what the HO's used.

GAAAAAAAH. I always forget to put my year/engine my jeep has. I just assume it's right next to my name like on other forums.

99/4.0/AW4/NP242 (I think they just watched the video and realized it's OBDII.)

I got the jeep home, left it on, pulled the intake off and sprayed some Triflow (i prefer it over WD-40) into the IAC opening. Opened/closed the throttle a little bit, then i sprayed some more in there and exercised the throttle more.

Pulled my battery cables off (took both cables off) for about 30 minutes and threw a battery charger on it. Let it charge fully and reconnected my cables.

Jeep has started up fine since, but if the problem comes back i'll be sure to post back.

Be careful what you spray into your intake. It's not always compatible with O2 sensors and can wipe them out.

A trigger sprayer and Deionized water might be the safest? Just keep it far away from the TPS!!!! Wrap the TPS first with plastic????

90% isopropyl alcohol in a trigger sprayer (not a mist but a stream spray?) maybe?

Brake cleaner ingredients vary all over the map now, not a good choice, carb cleaner can damage paint, I would not use Triflow (has Teflon in it, which releases Hydroflouric acid on combustion, nasty stuff, can eat the O2 sensor), any thing with silicone in it can KILL the O2 sensor fast....PB Blaster might damage the varnish on the IAC motor windings, and neither brake cleaner formula is a good idea for the IAC port. Flammable brake cleaner may be OK in the throttle body as a starter fluid, but non flammable brake cleaner should never go into a running engine intake, it releases HCL acid on combustion, nasty stuff!!! The non-flammable brake cleaner is OK for parts cleaning, even motor windings!!!!

And carb cleaner, throttle body cleaner and some brake cleaners can strip varnish off the IAC windings, causing a short, if you spray it in the IAC port directly.

WD-40 leaves a sticky wax based residue that is no good.

Ecomike said:

A trigger sprayer and Deionized water might be the safest? Just keep it far away from the TPS!!!! Wrap the TPS first with plastic????

90% isopropyl alcohol in a trigger sprayer (not a mist but a stream spray?) maybe?

Brake cleaner ingredients vary all over the map now, not a good choice, carb cleaner can damage paint, I would not use Triflow (has Teflon in it, which releases Hydroflouric acid on combustion, nasty stuff, can eat the O2 sensor), any thing with silicone in it can KILL the O2 sensor fast....PB Blaster might damage the varnish on the IAC motor windings, and neither brake cleaner formula is a good idea for the IAC port. Flammable brake cleaner may be OK in the throttle body as a starter fluid, but non flammable brake cleaner should never go into a running engine intake, it releases HCL acid on combustion, nasty stuff!!! The non-flammable brake cleaner is OK for parts cleaning, even motor windings!!!!

And carb cleaner, throttle body cleaner and some brake cleaners can strip varnish off the IAC windings, causing a short, if you spray it in the IAC port directly.

WD-40 leaves a sticky wax based residue that is no good.

Click to expand...

I use Loc Tite Multi spray (five way spray U.K./Carumba Multi spray Germany). The label says it is for electronics protection. One thing about Loc Tite (Henkel), it usually works as advertised, you just have to read the label.

I use WD 40 as a preservative and avoid using it on low voltage electrical. Break Free is a good preservative, PB Baster frees up rusted parts. A premium contact/electrical spray for cleaning connectors. I grease most everything taht moves with Lithium grease and Copper paste for high temps.

I've never had any issues with brake cleaner it is designed in most cases to be plastic and rubber compatible. There are plastic and rubber pieces in the brake system.

I avoid using Fluorocarbon based solvents (brake cleaner) You burn it under the right conditions and it makes Phosgene gas, nasty stuff.

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

They do make throttle body cleaning spray. No worrying about damaging anything using it.

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

Digger87xj said:

They do make throttle body cleaning spray. No worrying about damaging anything using it.

Click to expand...

Whatever you decide to use, I'd use sparingly. The drive for the piston in the IAC is lubricated and protected from corrosion by a grease. It would likely to be unwise to wash it all out with a solvent and leave it exposed to the elements.

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

Digger87xj said:

They do make throttle body cleaning spray. No worrying about damaging anything using it.

Click to expand...

I strongly disagree. Throttle body cleaner should not be used directly on the IAC. As 8Mud said, the threaded shaft needs lube that also acts as corrosion protection, an ultralight weight lube to be specific (I use vacuum pump oil as it will not gel or dry out, or gum up under a vacuum), and even throttle body cleaner will damage paint and eventually motor winding varnish so it is bad idea to use it directly on the IAC or in the IAC.

http://www.crcindustries.com/faxdocs/msds/5078.pdf

http://www.tompkins-co.org/msds/m3002.pdf

The ingredients in throttle body cleaner are common paint stripper ingredients.

Unfortunately, brake cleaner is no longer what it use to be here in the US (and you are in Germany....), the US state regs, like California, have mucked with the formulas here.

Here in Houston, the non flammable brake cleaner is either 100% Perchlorethylene (which is a great, safe, low cost electrical parts cleaner, the old mainstay formula used for decades), or Perchlorethylene with some oily hydrocarbon stuff that no longer dries right away making it useless for cleaning certain things, like electrical contacts.

The cheaper Flammable brake cleaners here use paint stripper ingredients like Toluene.:gag:

LocTite and Henkel do not seem to be in the aerosol business here.

8Mud said:

I use Loc Tite Multi spray (five way spray U.K./Carumba Multi spray Germany). The label says it is for electronics protection. One thing about Loc Tite (Henkel), it usually works as advertised, you just have to read the label.

I use WD 40 as a preservative and avoid using it on low voltage electrical. Break Free is a good preservative, PB Baster frees up rusted parts. A premium contact/electrical spray for cleaning connectors. I grease most everything taht moves with Lithium grease and Copper paste for high temps.

I've never had any issues with brake cleaner it is designed in most cases to be plastic and rubber compatible. There are plastic and rubber pieces in the brake system.

I avoid using Fluorocarbon based solvents (brake cleaner) You burn it under the right conditions and it makes Phosgene gas, nasty stuff.

Click to expand...

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

Don't care if you agree or not. Used it for years with absolutely no ill effect.

Re: Cranks & Cranks Unless Gas Pedal Is Depressed.

Digger87xj said:

Don't care if you agree or not. Used it for years with absolutely no ill effect.

Click to expand...

I kinda got that impression. My comment was for others here that "MIGHT care", and might wish to learn something new.

Last time a mechanic told me

"I used it for years with absolutely no ill effect",

he wiped out the gear box seals on an old rig of mine using transmission fluid in my power steering pump. :doh:

That is one of the reasons I do all my own mechanic work now.

Well problem is back.

Cranks and cranks no start unless pedal is depressed.

I have to manually idle it and put it into gear to get going. If I release the gas pedal at all within ~20 seconds it stalls.

After that though it runs fine and idles normally. Only on start up and for the first few running seconds.

Time for a new IAC?

Kingkong0192 said:

Well problem is back.

Cranks and cranks no start unless pedal is depressed.

I have to manually idle it and put it into gear to get going. If I release the gas pedal at all within ~20 seconds it stalls.

After that though it runs fine and idles normally. Only on start up and for the first few running seconds.

Time for a new IAC?

Click to expand...

That is the question, I'd check the voltage at the battery terminals with the motor running and again after the motor has been off for a few hours. Maybe clean the IAC connector.

I've had mine act up numerous times, I still have the original IAC on all my XJ's. I do have another alternator and on another occasion a new battery, twice, on two different XJ's both with occasional IAC issues. I did replace one IAC, it failed after a year. I cleaned the old OEM original, lubricated it and put that in there around 5-6 years ago.

I have had to repeat the cleaning a few times over a period of a couple of weeks to get it to be reliable. Seems the stuff you blow out the first time gets replaced or the crap migrates to problem spot again.

Some guys say to blow out the TB with and the intake with solvent. And wash all that crap by the valves, into the cylinder and out the exhaust. Sounds good in theory, but that sticky stuff catches fine silicates that make it through the air filter and that stuff stuck to the inside of the TB and intake is concentrated fine abrasive (polishing compound). What I'm essentially saying is washing a little bit down the intake is unlikely to hurt much (IMO), washing a lot down the intake may cause issues. It may even cause some major issues, like a lump of stuff getting caught on the valve seat, burning on there and keeping the valve from closing.

It's 4 bolts, some clips, a few screws, and a couple of connectors. Pull the TB, disassemble it, inspect/clean the IAC passage, clean the pintle without having to worry about whatever solvent you sprayed into it knocking the grease off of it... or letting you put something on it if it's sticking.